1. Technical Field
The present disclosure relates generally to micro electro-mechanical systems, and more particularly to forming at least one suspended electrode and a second electrode separated by a submicron opening.
2. Description of the Related Art
Micro electro-mechanical systems (MEMS) in semiconductors have arisen for various applications such as to sense temperature, pressure, strain, acceleration, rotation, and chemical properties of liquids and gases. Those MEMS structures are usually combined with other integrated circuits, such as complimentary metal oxide semiconductor (CMOS) circuits, for analyzing and calculating the parameters sensed by MEMS. Therefore, the MEMS manufacturing processes are required to be compatible with the existing MOS or CMOS manufacturing processes such that the whole system is inexpensive, reliable, and compact.
Various MEMS structures and materials have been proposed and developed for such sensing purposes. Sensing may be accomplished by capacitively coupled electrodes separated by an air gap. As one or both of the electrodes move relative to the other electrode a fluctuation in the capacitive air gap results in a change in the capacitance. The sensitivity of capacitively coupled electrodes increases as a distance between the electrodes is reduced. Device performance may also be improved by maximizing a ratio of a surface area of the electrodes to the distance between two electrodes.
Alternatively, the sensitivity of the capacitively coupled electrodes may be varied by changing dimensions and area of the material used to form the electrodes. This is accomplished by changing the surface area, the width, the length, or the height of the MEMS structure to modify the device performance.
Currently inertial sensors and other capacitively coupled electrodes are typically silicon based, such as polysilicon, bulk silicon, or epitaxially grown silicon.